Anaerobic fermentation method and apparatus

ABSTRACT

A method and apparatus for monitoring a liquid undergoing anaerobic fermentation in a vessel is disclosed. The apparatus comprises an airlock containing a fluid for sealing the vessel and means to detect passage of bubbles through the airlock.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a Continuation-in-Part of U.S. applicationSer. No. 10/289,033, filed Nov. 6, 2002, incorporated by referenceherein.

REFERENCE TO COMPUTER PROGRAM LISTING APPENDIX

[0002] This patent includes a computer program listing appendix oncompact disc. Two duplicate compact discs are provided herewith. Eachcompact disc contains a computer program listing as follows:

[0003] Filename: Fermentometer_Interface3.vbp

[0004] Size: 2 kilobytes

[0005] Date Created: Aug. 20, 2003

[0006] Filename: Main2.frm

[0007] Size: 61 kilobytes

[0008] Date Created: Aug. 20, 2003

[0009] Filename: Module1.bas

[0010] Size: 1 kilobyte

[0011] Date Created: Aug. 20, 2003

[0012] Filename: patent01.c

[0013] Size: 20 kilobytes

[0014] Date Created: Aug. 20, 2003

[0015] Filename: hc11.h

[0016] Size: 4 kilobytes

[0017] Date Created: Aug. 20, 2003

[0018] Filename: _const.h

[0019] Size: 1 kilobyte

[0020] Date Created: Aug. 20, 2003

[0021] Filename: stdio.h

[0022] Size: 1 kilobyte

[0023] Date Created: Aug. 20, 2003

[0024] The computer program listing appendix is hereby expresslyincorporated by reference in the present application.

FIELD OF THE INVENTION

[0025] The present invention relates generally to a method and apparatususeful during anaerobic fermentation, and more particularly to a methodand apparatus for measuring the volume and rate of gas produced duringanaerobic fermentation, this invention having particular utility duringthe making of alcoholic beverages.

BACKGROUND OF THE INVENTION

[0026] It is common when making alcoholic beverages in the home to placethe liquid subject to fermentation into a vessel for anaerobicfermentation, the vessel being closed by a fermentation airlock. Thepurpose of the fermentation airlock is to prevent undesirable dust andbacteria from contaminating the material being fermented. Therefore itis common to utilize an airtrap, the gas produced by fermentationbubbling though a liquid in the airtrap, the liquid typically containingwater and a sterilizing agent such as sodium or potassium metabisulfite.Differing types of fermentation locks are employed, various examplesbeing shown in U.S. Pat. Nos. 4,517,884, 4,842,869, and 5,950,524. Afavorite form of airlock is the “S” type airlock, variations being shownin U.S. Pat. Nos. 2,023,153 and 4,717,031, and German patents 412,918and 957,563. Another prior art form of “S” type airlock is shown in FIG.1 of this application.

[0027] The airlock may be molded from a clear plastic, all airlocksbeing quite uniform in size. It has been observed that when using someairlocks that each bubble has substantially the same volume, i.e., 1.7ml. It is also known that during fermentation that equal mole volumes ofCO₂ and alcohol are produced.

SUMMARY OF THE INVENTION

[0028] The present invention broadly comprises a method and apparatusfor measuring gas produced during anaerobic fermentation. The methodcomprises the steps of counting bubbles which pass through said airlockto determine a volume of gas produced and determining the amount ofalcohol produced based on the volume of gas produced.

[0029] The above objects, and other objects and advantages of thisinvention will become more apparent to those skilled in the art after aconsideration of the following detailed description taken in conjunctionwith the accompanying drawings in which a preferred form of thisinvention is illustrated.

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] It should be appreciated that, in the detailed description of theinvention which follows, like reference numbers on different drawingviews are intended to identify identical structural elements of theinvention in the respective views.

[0031]FIG. 1 illustrates a prior art “S” type airlock;

[0032]FIG. 2 illustrates an airlock of a first embodiment of the presentinvention, an airlock being provided with electrodes;

[0033]FIG. 3 shows a dust cap for the modified “S” type airlock, whichdust cap is provided with suitable contacts for contacting theelectrodes in the modified “S” type airlock;

[0034]FIG. 4 shows a first embodiment of the present invention with theairlock being mounted on a vessel suitable for anaerobic fermentation;

[0035]FIG. 5 shows a bubble interrupting the flow of current throughbetween the electrodes, signaling a bubble event;

[0036]FIG. 6 shows an embodiment of the electrical circuit of thecontrol means;

[0037]FIG. 7 shows an alternate embodiment of the electrical circuit ofthe control means;

[0038]FIG. 8 illustrates a second embodiment of an airlock of thepresent invention;

[0039]FIG. 9 illustrates a third embodiment of an airlock of the presentinvention;

[0040]FIG. 10 illustrates a fourth embodiment of an airlock of thepresent invention;

[0041]FIG. 11 illustrates a fifth embodiment of the present invention,comprising an optical sensor and communication means;

[0042]FIG. 12 illustrates an embodiment of the present invention whereinmultiple control means are connected to a single communication controlmeans;

[0043]FIG. 13 illustrates an alternate embodiment of the presentinvention wherein multiple control means are connected to a singlecommunication control means;

[0044]FIG. 14 illustrates a schematic of the electrical circuit for thefifth embodiment of the present invention, comprising an optical sensor;

[0045]FIGS. 15 and 16 illustrate an embodiment of the present inventionwherein the optical detector is arranged to mate with a portion of anairlock having two parallel sides and two arcuate sides;

[0046]FIGS. 17 and 18 illustrate an embodiment of the present inventionwherein the optical detector is arranged to mate with a portion of anairlock having a rectangular cross section; and,

[0047]FIGS. 19 and 120 illustrate an embodiment of the present inventionwherein the optical detector is arranged to mate with a portion of anairlock having a hexagonal cross section.

DETAILED DESCRIPTION

[0048] With reference initially to FIG. 1, an airlock is illustrated,said airlock being indicated generally at 10. This airlock consists of amolded clear plastic member indicated generally at 12, the plasticmember including an “S” shaped passageway which will be described later.Extending downwardly from the “S” shaped passageway is a mounting stem14 which is inserted into the rubber bung or cork 16 of a fermentingvessel 18 so as to be an airtight fit. The airlock is provided with adust cap 20 at its upper end.

[0049] The “S” shaped passageway includes an upwardly extending portion22 which is in direct communication with the stem 14, the portion 22being essentially cylindrical in cross section. A “U” shaped member 24having a circular cross section connects the portion 22 with adownwardly extending portion 26 having upper, intermediate, and lowerbulbs 26.1, 26.2, and 26.3, respectively. A further “U” shaped member 28having a circular cross section connects the lower end of the downwardlyextending portion 26 with an upwardly extending portion 30 provided withupper, intermediate and lower bulbs 30.1, 30.2, and 30.3, respectively.An upwardly extending member 32 is provided with a bulb 34 at its topend, which bulb receives the dust cap 20. A clear plastic web orflashing 36 extends between the downwardly extending portion 26 and theupwardly extending portion 30, and also between the downwardly extendingportion 26 and the upwardly extending portion 22 to keep the variousparts in fixed relationship to each other.

[0050] After the liquid to be fermented is placed in the vessel, whichliquid may be a wine must, the vessel is sealed with an airlock at thecommencement of anaerobic fermentation. To this end, a sterilizingliquid is placed in the “S” shaped airlock, the sterilizing liquidfilling the “U” shaped member 28 and ½ of each of the lower bulbs 26.3and 30.3, the sterilizing liquid being indicated generally at SL in FIG.2. The sterilizing liquid typically contains either sodium or potassiummetabisulfite, although other sterilizing agents may be used. Duringanaerobic fermentation the yeast is less active than during the initialaerobic fermentation, and the CO₂ produced with escape through thesterilizing liquid one bubble at a time.

[0051] With reference to FIG. 2, it can be seen that the “S” typeairlock of the present invention is provided with two electrodes 40, 42.Electrode 40 is embedded in the flashing 36 which extends between thedownwardly extending portion 26 and the upwardly extending portion 30.Additional flashing 44 is provided to one side of the upwardly extendingportion 30 for the receipt of electrode 42. As can be seen from FIG. 2,the electrodes have lower terminal ends that extend into the passageway28. Normally the ends of the electrodes are covered with the sterilizingliquid, which conducts electricity. Thus, when a voltage is appliedbetween them, current flows between the electrodes. However, when abubble passes through the tube 28, the current flow between theelectrodes is interrupted. Dust cap 20, shown in FIG. 3, prevents dustfrom settling into the airlock when it is engaged with the top ofairlock 12. Conducting members 21 connect to electrodes 40 and 42.

[0052] As illustrated in FIG. 4, electrodes 40 and 42 are connected tocontrol means 60 through conducting members 21. Control means 60comprises control buttons 65A, 65B, 65C, 65D, and 65E, and a display 70.Bottle 18 contains wine must W. Control means 60 counts the number oftimes the current between electrodes 40 and 42 is interrupted. Controlmeans 60 determines the status of the fermenting liquid based on thehistory of bubbles detected. Control means 60 displays the status of thefermenting liquid on display 70.

[0053] The interruption of the current between the electrodes isillustrated in FIG. 5. Bubble 50, created by the production of CO₂during fermentation, envelops the exposed conductive material of bothelectrodes. Thus, with a low voltage drop across the electrodes, the gasdoes not conduct electricity between the electrodes. A preferred voltagedrop across the electrodes is approximately 5 V, although other voltagedrops might be suitable. The control means of the apparatus records eachinterruption in the current as a bubble event.

[0054]FIG. 6 is a schematic of an embodiment of the electrical circuitof the control means. The circuit shown comprises electrodes 40 and 42,a 5 V source, resistor 85, operational amplifier (op amp) 87, positiveand negative power supplies V₊ and V⁻ to power the op amp, and processor90. Processor 90 is a conventional microprocessor, well known to thosein the electronics art. The 5 V source is connected across electrodes 40and 42 through resistor 85. When current exists between the electrodes,V_(in−) is 0 V. (The 5 V source is shorted to ground.) However, when abubble interrupts the current through the electrodes, V_(in−) is nolonger zero. (Ground is separated from V_(in−) by an open circuit.)V_(in+) is connected to ground. Thus processor 90 can determine thepresence of a bubble between electrodes 40 and 42 from the output ofoperational amplifier 87.

[0055]FIG. 7 shows a second possible embodiment of control means 60.This embodiment comprises a plurality of control buttons 65A, 65B, 65C,65D, 65E, and 65F, electrodes 40 and 42, a 5 V source, resistor 89, pin88 of processor 90, audio alarm 92, and visual alarm 94. Pin 88 ofprocessor 90 is connected to electrode 40 and to a 5 V source throughresistor 89. Electrode 42 is connected to ground. When current existsbetween the electrodes, pin 88 is shorted to ground. When the current isinterrupted by a bubble, pin 88 will be lifted to a non-zero voltage.(The voltage level will depend on the resistance value of resistor 89).In this manner, processor 90 can determine the presence of bubblesbetween electrodes 40 and 42.

[0056] To use the above-described device, a measure volume of a liquidsubject to fermentation, such as a wine-must, is placed in a container.(This is typically done after a period of aerobic fermentation and ahydrometer measurement to determine the proportion of sugar remaining.)The airlock of the present invention is inserted in the neck of thecontainer. The user programs the volume of liquid present in thecontainer using the control buttons.

[0057] In a preferred embodiment, control means 60 are configured asfollows. First, the batch size must be set. Button 65A increases thebatch size by 10 liters each time it is pushed. Button 65B increases thebatch size one liter each time it is pushed. Button 65C accepts thebatch size when it is pushed, if the batch size is non-zero. (Buttons65D and 65E have no function in setup mode). After the batch size isset, the user can enter a user specified time alarm, to be activatedwhen the enter amount of time passes without a bubble being detected.Button 65A increases this alarm time by one hour each time it is pushed.Button 65B increases this alarm time by one minute each time it ispushed. Button 65C accepts the current alarm time. (Zero may be enteredif no user specified time alarm is desired.) When the user specifiedalarm is set, the user can then enter an alcohol alarm level. Button 65Aincreases the alcohol level alarm by one percent each time it is pushed.Button 65B increases the alcohol level alarm by one tenth of one percenteach time it is pushed. Button 65C accepts the current alcohol level.After the alcohol level alarm is set, the user can activate the 24 houralarm. Button 65A enables the 24 hour alarm. Button B disables the 24hour alarm. Button 65C accepts the current 24 hour alarm status. Thecontrol means then detects the bubbles of gas escaping from the airlockand displays the status of the liquid on display 70.

[0058] The status is determined based on the history of bubbles detectedby control means 60. In one embodiment, airlock 12 is configured suchthat the escaping bubbles have a volume at room temperature and 1atmosphere of pressure of 1.7 ml. (It is assumed that the fermentationis done at a constant temperature, thus an equal amount of gas iscontained in each bubble). Thus, by counting the number of bubbles,control means 60 can determine the amount of gas to escape from theairlock. According to calculations known in the art, the amount ofalcohol generated during anaerobic fermentation can be determined basedon the volume of CO₂ generated (assuming substantially all of theescaping gas is CO₂ generated by fermentation) and the amount of liquidpresent in the container (input using the control buttons, as discussedabove). Accordingly, control means 60 can calculate the volume ofalcohol generated and display this amount on display 70.

[0059] In a preferred embodiment the buttons of the control meansfunction as follows. Button 65A scrolls the display of the bubble eventstowards the most current event. Button 65B scrolls the display of thebubble events towards the least recent event. Button 65C deletes thedisplay of the displayed event if pressed alone. Button 65D caused thecontrol means to reenter setup mode. Button 65E silences current alarmsand calls up a screen to review past alarms. Display 70 is set to themost recent event when button 65E is released. When buttons 65C and 65Eare pressed simultaneously, past alarms are cleared.

[0060] As discussed above, a user can preprogram a percentage of alcoholdesired with the control buttons. In this case, control means 60displays a countdown of the amount of alcohol still to be generated.Control means 60 can include an audible alarm 94 and/or visual alarm 96to signal a user when the desired amount of alcohol has been produced.This can be especially useful in making beverages wherein somefermentation is desired after the liquid is bottled. The alarm can beset to alert the user when a portion of the desired alcohol has beenproduced. The user can then transfer the beverage to individual bottlesfor the remaining fermentation. This is also useful for the productionof a sweet beverage. The user can stop fermentation before all the sugarhas been consumed by the yeast. This alarm also allows a user to addfurther ingredients at different stages of the fermentation, such as theaddition of malolactic cultures, nutrients, and other ingredients knownin the art. The present invention allows for greater quality control inproduction by determining to a greater accuracy the proper time to addadditional ingredients.

[0061] Control means 60 also includes timing means to determine theamount of time between each bubble. Counting means displays the amountof time since the last bubble on display 70. Audible and/or visiblealarms can be activated to alert the user after a specified time withouta bubble has been reached. In one embodiment, this time period is 24hours. In another embodiment, this time period is set by the user usingthe control buttons (the user specified alarm discussed above).

[0062] A potential problem with fermentations that can take a longperiod of time is the evaporation of the sterilizing liquid. If thesterilizing liquid evaporated to the point wherein outside air may passinto vessel 18, then the fermentation may be spoiled. The presentinvention warns a user when the level of the sterilizing liquid is low.Electrodes 40 and 42 are placed in member 28 such that they are exposedto air before the liquid level drops to an extent that air could reentervessel 18, as shown in FIG. 2. Control means 60 times the length of thebubbles. If the sterilizing liquid has partially evaporated, then theelectrodes will be exposed to air continuously. Thus, when control means60 detects an interruption of the current that lasts an extended periodof time (in one embodiment 1 hour), it displays a low liquid levelwarning on display 60. Audible and/or visible alarms may also beactivated. In addition, bubble detection indicator 92 is lit when abubble is being detected (when current is not flowing between electrodes40 and 42.) This can also allow a user to determine there is a problemif the bubble detection indicator remains lit for an extended period oftime. The low liquid level warning and bubble detection indicator allowa user to replace the lost sterilizing liquid before the fermentingliquid is spoiled.

[0063]FIGS. 2, 4, and 5 show the present invention being practiced withan “S” type airlock. However, it should be readily apparent to oneskilled in the art that other airlocks or valves may be modified topractice the present invention. FIGS. 8-10 illustrate several valvesknown in the art. FIG. 8 shows a flapper check valve 110. Electrodes 140and 142 contact conducting strip 145 on flapper 115 when the valve isclosed. Thus, when the valve is closed, current flows from electrode 140to electrode 142 through strip 145. When flapper 115 is forced open bygas pressure, the current flowing between electrode 140 and electrode142 is interrupted. Thus, the number of times gas escapes from the valvecan be counted. The amount of gas that escapes each time is measured andprogrammed into control means 60. In this manner, a fermentation processcan be monitored as described above. In a similar manner, FIG. 9 shows apiston check valve 210 comprising electrodes 240 and 242, and valvemember 215 having conducting strip 245 on a surface thereon. When thevalve is closed, current flows from electrode 240 to electrode 242through strip 245. When member 215 is forced open by gas pressure, thecurrent flowing between electrode 240 and electrode 242 is interrupted.FIG. 10 shows ball check valve 310 comprising electrodes 340 and 342 andconducting ball 345. When the valve is closed, current flows fromelectrode 340 to electrode 342 through conducting ball 345. When ball345 is forced up by gas pressure, the current flowing between electrode340 and electrode 342 is interrupted. The amount of gas released eachtime the valve opens is used to determine how much gas is producedduring fermentation, in the manner described above. These modifications,including the use of the practicing of the present invention with othervalves not shown, is intended to be within the spirit and scope of theinvention as claimed. In the present specification and claims, the word“airlock” is intended to mean any airlock or valve known in the art orhereafter developed that can be modified as described herein to practicethe present invention.

[0064] An embodiment of the present invention may be arranged to havethe elevation of the apparatus entered using the control buttons orthrough the communication means described below. The processing meansadjusts the calculated alcohol percentage by volume based on thealtitude of the apparatus. This corrected alcohol percentage by volumeis used in computing the amount of alcohol present in the solution beingfermented. An embodiment of the present invention can also include aflow rate alarm, where the flow rate, for example computed in cubiccentimeters of alcohol produced per hour per liter of liquid, can becorrected based on the elevation of the apparatus. When the flow rate ofalcohol exceeds a threshold in put by a user, the alarm is sounded. Thismay be a visual or optical alarm, as discussed above. Software thatimplements the above-described functions is included in the appendix.

[0065] An embodiment of the present invention including communicationmeans 480 is shown in FIG. 11. Apparatus 410 comprises control means460, display 470, and communication control means 475. Control means 460comprises control buttons 465A, 465B, 465C, 465D, and 465E. Apparatus410 also includes optical sensor 450 arranged to mate with portion 428of airlock 412. Wire 448 connects sensor 450 to control means 460.Airlock 412 contains sterilizing liquid SL. The display and controlbuttons function as described above for the first embodiment.Communication control means 475 communicates with information system 490with communication means 480. Communication means 480 may comprise ahard wire or a wireless connection, both of which are known in the art.Information system 490 may comprise a single personal computer, a localarea network, a wide area network such as the Internet, a wireless phonesystem, a pager system, a personal digital assistant system, or anyother information system known in the art. Thus, apparatus 410 isarranged to transmit and receive messages over communication means 480to and from information system 490. (For example, the appendix containsa software listing that, when loaded on a general purposemicroprocessor, transmits messages to a digital cellular phone.)

[0066] The apparatus may receive parameters for programming theapparatus from the information system. Thus, a local personal computer,a computer connected to the Internet, a personal digital assistant, orany of the other information system known in the art may be used toprogram the present invention. The apparatus may transmit the status ofany of the above-described alarms to any of the information systemsknown in the art. Thus, for example, a user can be warned by cell phone,pager, or personal digital assistant that the alcohol alarm is active.The status of the fermentation may be emailed to a user, or it may beposted on a website. The communication means can receive all of theparameters used to program the control means, as discussed above, suchas altitude, batch size, user specified time alarm setting (alarmactivated when no bubbles are detected for specified time), alcohollevel alarm (alarm activated when alcohol level reaches specifiedlevel), and enabling/disabling the 24 hour alarm. The data received bythe communication means can comprise commands to clear any specificalarm, or all alarms. The data transmitted by the communication meanscan comprise: alcohol level, alarm status, time since the last bubbledetection, bubble count, or any other parameter stored in the controlmeans. It should be readily apparent to one skilled in the art thatother parameters may be used by the control means, and these parametersmay be sent over the communication means. These modifications are withinthe spirit and scope of the invention as claimed. The communicationmeans may transmit messages using RS-232 protocol, Transfer ControlProtocol/Internet Protocol (TCP/IP), Universal Serial Bus (USB)protocol, or any other protocol known in the art. (For example, thesoftware listing in the appendix, when loaded on a conventional generalpurpose microprocessor, sends messages using the RS-232 protocol.) Itshould be readily apparent to one skilled in the art that othercommunication means and information systems are possible, and thesemodifications are within the spirit and scope of the invention asclaimed.

[0067] An embodiment of the present invention may also be configured tolog the data sent to and received form the control means. This allows auser to evaluate the batch either by comparison to an idealfermentation, or comparison to other fermentation batches, for examplegraphically. It should be readily apparent to one skilled in the artthat data from the present invention can be logged into a databaseprogram and displayed graphically, with commercially available softwarepackages, as described above.

[0068]FIG. 12 illustrates an embodiment of the present invention whereincommunication control means 475 sends and receives data from multiplecontrol means 460A, 460B, and 460C. Communication control means 475communicates with information system 490 over communication means 480.Communication control means 475 comprises at least one port 477. Asshown in FIG. 12, control means 460A, 460B, and 460C are each connectedto communication control means 475. The connection is made by connectingwire 478 between port 477 of communication control means 475 and port462 of control means 460A, 460B, and 460C, respectively. FIG. 13 showsanother embodiment of the present invention wherein control means 460A,460B, and 460C are daisy chained together. Control means 460A isconnected to control means 460B with a wire 478 connected between port462 of control means 460A and port 462 of control means 460B. Controlmeans 460B is connected to control means 460C with a wire 478 connectedbetween port 462 of control means 460B and port 462 of control means460C. Control means 460C is connected to communication control means 475with a wire 478 connected between port 462 of control means 460C andport 477 of communication control means 475. As should be readilyapparent to one skilled in the art, any combination of directconnections to a communication control means and daisy chaining multiplecontrol means are possible, and these modifications are within thespirit and scope of the invention as claimed. The present invention mayalso be practiced as shown in FIG. 11, wherein communication controlmeans 475 is integral with control means 460. In this case, each controlmeans 460 communicates with the information system 490 through itsrespective communication control means 475. It should be readilyapparent to one skilled in the art that the control means 460 shown inFIGS. 12 and 13 may comprise optical sensors as shown in FIG. 11, or maycomprise two electrodes, as shown in FIG. 4. Any bubble countingapparatus comprising communication means for transmitting and receivingdata to and from an information system is within the spirit and scope ofthe invention as claimed.

[0069]FIG. 14 is a schematic of an exemplary embodiment of an electricalcircuit for an embodiment of the present invention comprising opticalsensor 450. Sensor 450 comprises optical beam emitter 452 and opticalbeam detector 454. In the embodiment shown, emitter 452 is an LED anddetector 454 is a phototransistor. Beam emitter 452 emits a light beamtowards detector 454. The beam passes through the wall 428A of airlockportion 428. Wall 428A is normal to the line connecting emitter 452 anddetector 454. Thus, the beam enters the interior of airlock portion 428normal to the surface of wall 428A. If no bubble is present in thesterilizing liquid, the beam passes through the sterilizing liquid,through wall 428B of the airlock portion 428, and is incident ondetector 454. When light is incident on phototransistor 454, current mayflow through the phototransistor. This shorts connection 456 to ground.When bubble 50 passes through airlock portion 428, the edges 52 willrefract the incident light that is propagating in a direction normal towalls 428A and 428B in a direction that is not normal to walls 428A and428B. Thus, when bubble edge 52 is located between emitter 452 anddetector 454, light will not be incident on detector 454. This disablescurrent from flowing through phototransistor 454, which isolates pin 456from ground. The 5 V source pulls pin 456 up to 5 V. When the bubble isbetween the emitter and detector, the beam passes through the gasmixture to the detector. This allows current to flow through thephototransistor, pulling pin 456 down to 0 V. Thus, for each bubble thatpasses through airlock portion 428, the light beam will be interruptedbriefly twice by each bubble edge 52, leading to two voltage pulses of5V, compared to the normal value of 0V. Pin 456 is connected to ageneral purpose microprocessor programmed to monitor the voltagetransitions at pin 456 between 0 V and 5 V. Thus, the processorincrements the bubble count by 1 for each pair of interruptions of thelight beam (each pair of 5 V pulses at pin 456). Optical sensor 450 maycomprise a sensor such as the Omron® EE-SX198, EE-SX199, EE-SX1018,EE-SX1025, EE-SX1041, EE-SX1042, E-SX1070, or EE-SX1071, available fromOmron Corporation, Shiokoji Horikawa, Shimogyo-ku, Kyoto, 600-8530Japan. The processor is programmed to use the bubble count as describedabove for the first embodiment. The appendix contains a software listingfor a processor using the optical sensor of the present embodiment.

[0070] It should be readily apparent to one skilled in the art that anyairlock may be used with the embodiment comprising an optical sensor,providing it comprises a portion with two parallel sides. For example,FIGS. 15 and 16 show optical sensor 450 arranged to detect bubblespassing through airlock portion 428 having two parallel sides 428A and428B, and two arcuate sides 428C. FIGS. 17 and 18 show optical sensor450 arranged to detect bubbles passing through airlock portion 428having a rectangular cross section, with two parallel sides 428A and428B and two parallel sides 428D that are perpendicular to sides 428Aand 428B. FIGS. 19 and 20 show optical sensor 450 arranged to detectbubbles passing through airlock portion 428 having two parallel sides428A and 428B, and sides 428E that form a hexagonal cross section. Itshould be readily apparent to one skilled in the art that airlockshaving portions with cross sections of other shapes, with two parallelsides are possible, and these modifications are within the spirit andscope of the invention as claimed.

[0071] While a preferred form of this invention has been described aboveand shown in the accompanying drawings, it should be understood thatapplicant does not intend to be limited to the particular detailsdescribed above and illustrated in the accompanying drawings, butintends to be limited only to the scope of the invention as defined bythe following claims. In this regard, the term “means for” as used inthe claims is intended to include not only the designs illustrated inthe drawings of this application and the equivalent designs discussed inthe text, but it is also intended to cover other equivalents now knownto those skilled in the art, or those equivalents which may become knownto those skilled in the art in the future.

What is claimed is:
 1. A method for determining an amount of alcoholproduced during anaerobic fermentation in a sealed anaerobicfermentation vessel containing a liquid being fermented, said vesselsealed with an airlock, the method comprising the steps of: countingbubbles which pass through said airlock to determine a volume of gasproduced, said bubbles detected by an optical detector; and, determiningsaid amount of alcohol produced based on said volume of gas produced. 2.The method recited in claim 1 further including the step of determiningthe interval between bubbles so that the rate of fermentation may bedetermined.
 3. The method recited in claim 1 further including the stepof activating an alarm when a desired amount of alcohol is produced. 4.The method recited in claim 1 wherein said airlock is an “S” typeairlock.
 5. The method recited in claim 1 further including the step ofcorrecting said amount of alcohol produced based on an elevation of saidvessel.
 6. A method for measuring gas produced during anaerobicfermentation comprising the steps of: providing a vessel suitable foranaerobic fermentation; placing liquid materials subject to anaerobicfermentation within the vessel; sealing the vessel with an “S” typeairlock; and, counting the bubbles which pass through the airlock todetermine the volume of gas produced, said bubbles detected by anoptical detector.
 7. The method recited in claim 6 further comprisingthe step of determining the interval between bubbles so that the rate offermentation may be determined.
 8. An apparatus for monitoring a liquidundergoing anaerobic fermentation in a vessel, comprising: an airlockcontaining a fluid for sealing the vessel; and, an optical detectoroperatively arranged to detect passage of bubbles through said airlock.9. The apparatus recited in claim 8 wherein said airlock is an “S” typeairlock.
 10. The apparatus recited in claim 9 wherein said airlockcomprises a portion with two parallel sides.
 11. The apparatus recitedin claim 10 wherein said optical detector engages said portion of saidairlock having two parallel sides.
 12. The apparatus recited in claim 8further comprising means for determining the volume of gas producedbased on said detected passage of bubbles.
 13. The apparatus recited inclaim 12 further comprising: means to determine an amount of alcoholproduced based on said amount of gas produced, said amount correctedbased on an altitude of said apparatus; and, a display operativelyarranged to display said amount of alcohol produced.
 14. The apparatusrecited in claim 13 further comprising: an alarm operatively arranged towarn a user when a preprogrammed amount of alcohol has been produced.15. The apparatus recited in claim 8 further comprising: means fordetermining the time between bubble detections; and, means fordetermining the rate of gas production based on said time between bubbledetections.
 16. The apparatus recited in claim 15 further comprising: analarm operatively arranged to warn a user when no bubbles are detectedfor a predetermined amount of time.
 17. The apparatus recited in claim16 wherein said predetermined amount of time is 24 hours.
 18. Theapparatus recited in claim 8 further comprising: means for determiningthe length of time a bubble is proximate said optical detector; and, analarm operatively arranged to warn a user when the liquid in saidairlock is low, based on said length of time said bubble is proximatesaid optical detector.
 19. The apparatus recited in claim 13 furthercomprising means for computing a flow rate of alcohol produced, saidflow rate corrected based on an elevation of said apparatus.
 20. Theapparatus recited in claim 19 further comprising alarm means forsignaling when said computed flow rate exceeds a flow rate threshold setby a user.
 21. An airlock comprising: a portion having a cross sectionwith two parallel sides.
 22. The airlock recited in claim 21 whereinsaid portion has a polygonal cross section.
 23. The airlock recited inclaim 21 wherein said portion has a rectangular cross section.
 24. Theairlock recited in claim 21 wherein said cross section of said portionfurther comprises two opposing, arcuate sides.
 25. An apparatus formonitoring anaerobic fermentation comprising: an airlock; a bubbledetector; processing means connected to said detector, said processingmeans operatively arranged to count a number of bubbles passing throughsaid airlock; and, communication means connected to said processingmeans, said communication means operatively arranged to communicate databetween said processing means and an information system.
 26. Theapparatus recited in claim 25 wherein said airlock comprises a portionhaving two parallel sides.
 27. The apparatus recited in claim 25 whereinsaid processing means comprises a general purpose microprocessorprogrammed to count said number of bubbles passing through said airlock.28. The apparatus recited in claim 25 wherein said processing means isoperatively arranged to determine a quantity of alcohol produced by saidanaerobic fermentation.
 29. The apparatus recited in claim 25 whereinsaid processing means is operatively arranged to measure a period oftime between said bubbles passing through said airlock.
 30. Theapparatus recited in claim 25 wherein said processing means isoperatively arranged to determine when said anaerobic fermentation hasended.
 31. The apparatus recited in claim 25 wherein said processingmeans is operatively arranged to determine if said airlock contains aninadequate amount of liquid.
 32. The apparatus recited in claim 25wherein said data is said amount of alcohol produced.
 33. The apparatusrecited in claim 25 wherein said data is an alarm status.
 34. Theapparatus recited in claim 25 wherein said data is a warning that aninadequate amount of liquid is in said airlock.
 35. The apparatusrecited in claim 25 wherein said data is a warning that said anaerobicfermentation has ended.
 36. The apparatus recited in claim 25 whereinsaid communication means is an RS-232 connection.
 37. The apparatusrecited in claim 25 wherein said communication means is a TCP/IPconnection.
 38. The apparatus recited in claim 25 wherein saidcommunication means is a USB connection.
 39. The apparatus recited inclaim 25 wherein said information system is the Internet.
 40. Theapparatus recited in claim 25 wherein said information system is apersonal computer.
 41. The apparatus recited in claim 25 wherein saidinformation system is a wireless phone system.
 42. The apparatus recitedin claim 25 wherein said information system is a pager system.
 43. Theapparatus recited in claim 25 wherein said information system is apersonal digital assistant system.
 44. The apparatus recited in claim 25wherein said information system is a wireless local area network. 45.The apparatus recited in claim 25 further comprising database means tostore said data.